BBC News Online science editor Dr David Whitehouse considers some of the ethical arguments that are raised by the first GM monkey

It was inevitable that eventually someone would genetically modify a primate. A rhesus monkey called Andi is proof that it has finally been done.

The same team of scientists almost did it in 1999 when George was born. But although it seemed then that the researchers had managed to alter his genetic make-up, the animal turned out not to have the required extra bits of DNA.

Millions of mice die each year to find cures for human disease

The researchers tried again and this time Andi does display the modification. A marker gene means a fluorescent molecule is produced in his cells. It is not very exciting but it is the principle which is important here. The technology is being proven.

Some will look at Andi and see a Frankenstein monster, a forerunner of a nightmare genetic future in which feeling creatures suffer at the hands of immoral scientists who do not care how they obtain their experimental data.

Others will see Andi as potentially one of the greatest advances in tackling human ailments. A living creature due respect but who can contribute to alleviating human misery.

GM technology is already widely used on other organisms. In laboratories worldwide, you can find transgenic mice, flies and worms. Millions are sacrificed each year in the search for new therapies for incurable human diseases.

Spinal repair

Without mice, cancer treatments would certainly be less advanced. Mice, of course, have their limitations. They do not suffer some diseases that afflict us and often treatments that work in mice do not work for humans.

The modifications will become more specific and more useful

So why not use an animal that is genetically much closer to humans - such as monkeys? Only about one gene in a hundred is different and even then sometimes by not very much. It might be that we could arrive at better answers, quicker and with fewer animals overall having to suffer experimentation.

It is possible, for example, that gene therapy in monkeys could help people with anaemia. Scientists have already injected human genes into monkey muscles. The gene stimulates the production of red blood cells and it may be possible to do the same in humans with a pill.

Scientists have also used stem cells - master cells that can develop into many tissue types - to repair damaged spinal cords in monkeys.

But the idea of using monkeys to model human diseases takes the ethical arguments into a new sphere, way beyond those that already rage over the use of rodents. Monkeys are creatures that are so much closer to human capacities and sentience.

Technology is advancing rapidly and the Oregon researchers behind Andi will doubtless refine their work so that specific changes can be made to their primates. So how far do you want to go? Science is asking you some big questions.